The objective of the proposed research is to ultrastructurally characterize gene transcription and nascent transcript processing, chromatin replication, and mRNA translation; and to determine how these structural characteristics can be related to the regulatory phenomena involved in these basic genetic processes. The cell types that will be used include Drosophila embryos (transcription, replication, and transcript), myeloma cell cultures (immunoglobulin genes), amphibian oocytes (transcription, 5S rRNA genes, and stored mRNA), sea urchin oocytes (stored mRNA and translation), Bombyx mori silk gland (translation). HeLa and monkey cells (adenovirus 2 and simian virus 40), and Escherichia coli (transcription and translation). The methods that will be used include high resolution bright and darkfield electron microscopy, immunoelectron microscopy, electron microscopic autoradiography, isolation of cellular and nuclear components by various centrifugation procedures, protein purification by preparative gel electrophoresis, differential positive metal staining, negative staining, and enzymatic digestion and other chemical probes of structural organization. These studies should provide new information on structural aspects of genome organization during functional stages, the interactions within RNA polymerase-chromatin template-nascent product complexes, nuclear packaging and processing of RNA, and the interactions between ribosomes and mRNP molecules.